Conventional combines have sieves that function to separate kernels of grain from chaff and other foreign objects. The sieve is constructed of spaced apart slats mounted in parallel relation. A pivot bracket is mounted at one end of each slat. The pivot brackets are connected together with a slat connection member such as shown in U.S. Pat. No. 4,712,568, to Strong et al. As the slat connection member is moved fore and aft the slats are rotated in a manner similar to the operation of a Venetian blind. The rotation causes the openings in the sieve to open and close.
If the openings in the sieves are not adjusted properly, a combine will throw a considerable amount of grain away with the chaff. On older combines, the operator may not even be aware this is happening. Newer combines usually have a "grain loss monitor" in the exhaust path. But even when this instrument begins to show a loss trend, in most instances the operator still has to get out of the cab, walk to the rear of the combine, and then manually adjust the openings in the sieves. Sometimes he has to perform this operation several times as he "homes in" on the correct opening in the sieves for the grain conditions being encountered.
Several patents have addressed the problem of enabling a combine operator to adjust the sieve openings. For example, see U.S. Pat. No. 4,712,568, to Strong et al. This patent shows a handle for manipulating the sieve openings. U.S. Pat. No. 4,897,072 to Bestland shows a flexible pipe mechanically connected between a sieve and the cab of a combine so that an operator can turn a crank in the cab to mechanically adjust the opening of a single sieve. With this apparatus a single hand crank is associated with a single sieve and the apparatus provides no indication as to how far open or how far closed each sieve is adjusted when turning the crank.
From the above it can be seen that what is needed is a remote sieve adjusting apparatus which can easily control the sieve openings from a combine cab and further provide a visual indication as to how far the sieve openings are opened or closed.